The present invention relates to smoking articles such as cigarettes, and in particular, to cigarettes having filter elements containing a carbonaceous material.
Popular smoking articles, such as cigarettes, have a substantially cylindrical rod shaped structure and include a charge of smokable material such as shredded tobacco (e.g., in cut filler form) surrounded by a paper wrapper thereby forming a so-called "tobacco rod." Normally, a cigarette has a cylindrical filter element aligned in an end-to-end relationship with the tobacco road. Typically, a filter element includes cellulose acetate tow circumscribed by plug wrap, and is attached to the tobacco rod using a circumscribing tipping material. It also has become desirable to perforate the tipping material and plug wrap, in order to provide dilution of drawn mainstream smoke with ambient air.
Cigarettes are employed by the smoker by lighting one end thereof and burning the tobacco rod. The smoker then receives mainstream smoke into his/her mouth by drawing on the opposite end (e.g., the filter end) of the cigarette.
Certain cigarettes have filter elements which incorporate materials such as carbon. Exemplary cigarettes and filters therefor are described in U.S. Pat. Nos. 3,353,543 to Sproull et al. and 4,481,958 to Ranier et al. Certain commercially available filters have particles or granules of carbon (e.g., an activated carbon material or an activated charcoal material) dispersed within cellulose acetate tow; other commercially available filters have carbon threads dispersed therein; while still other commercially available filters have so-called "cavity filter" or "triple filter" designs. Exemplary commercially available filters are available as SCS IV Dual Solid Charcoal Filter from American Filtrona Corp.; Triple Solid Charcoal Filter from FIL International, Ltd.; Triple Cavity Filter from Baumgartner; and ACT from FIL International, Ltd.
Cigarette filter elements which incorporate carbon have a propensity to remove certain gas phase components from the mainstream smoke which passes through the filter element during draw by the smoker. However, aerosol particles of the smoke can have a tendency to interact with the carbon present within such conventional filter elements, thereby causing such aerosol particles to undergo a change in their chemical and physical character or nature. Such a change in the nature or character of aerosol particles of the mainstream smoke results in a change in the organoleptic properties of the mainstream smoke. For example, the mainstream tobacco smoke which is filtered using a conventional cigarette filter element incorporating carbon can often be characterized as having slightly metallic, drying and powdery flavor characteristics.
It would be desirable to provide a cigarette filter element which is capable of removing significant amounts of certain gas phase components of mainstream cigarette smoke, while not adversely affecting the flavor of that mainstream smoke to any significant degree.